Datasheet

1.3 System clock distribution
These series contain three on-chip clock sources:
• Internal clock source (ICS) module — The main clock source generator providing
bus clock and other reference clocks to peripherals
• External oscillator (XOSC) module — The external oscillator providing reference
clock to internal clock source (ICS), the real-time clock counter clock module (RTC)
and other MCU sub-systems.
• Low-power oscillator (LPO) module — The on-chip low-power oscillator providing
1 kHz reference clock to RTC and watchdog (WDOG).
NOTE
For this device, the system clock is the bus clock.
The following figure shows a simplified clock connection diagram.
ICSLCLK
ICSFFCLK
XTAL
EXTAL
RTC
FTM0
MTIM0
FTM1
MTIM1
FTM2ADC
SPI0
CPU
BDC
IIC
FLASH
ACMP
RAM
LPOCLK
ICS
SCI0
OSC
OSCOUT
1-kHz
LPO
ICSIRCLK
CRC
IPCDBG
2
N
CLKOUT
ICSCLK ( )
CLKOE
SCI1
SCI2
SPI1
DELAY
System Control
TCLK0 TCLK1
TCLK2
WDOG
~8 MHz after reset
BUSREF
1/2
1
KBI0
KBI1
Figure 1-2. System clock distribution diagram
The clock system supplies:
System clock distribution
MC9S08PA60 Reference Manual, Rev. 1, 9/2012
36 Freescale Semiconductor, Inc.